Cigarette Filter

ABSTRACT

The present invention relates to a cigarette filter that includes a multiple section filter which reduces the level of predetermined smoke constituents. The filter consists of a fibrous filter plug located at the mouth-end of the cigarette, a section containing a selective adsorbent material, and a section containing a general adsorbent material. The selective adsorbent material, such as a phenol-formaldehyde resin matrix surface-functionalized with mainly primary and secondary amine functional groups, removes specific smoke constituents from the tobacco smoke. The general adsorbent material, such as activated charcoal, is preferably capable of adsorbing a range of chemical compounds without a high degree of specificity. Structurally, the fibrous filter plug, the selective adsorbent section, and the general adsorbent section are in tandem and are circumscribed with a plug wrap.

CROSS-REFERENCE TO RELATED PATENT APPLICATIONS

[0001] This application claims priority from U.S. Provisional Application Ser. No. 60/309,388, filed Aug. 1, 2001, which application is incorporated herein by reference in its entirety, and from U.S. Provisional Application Ser. No. 60/309,435, filed Aug. 1, 2001, which application is incorporated herein by reference in its entirety.

BACKGROUND

[0002] The present invention relates to a cigarette filter that includes a smoke constituent adsorbent which, when combined with a carbon-based filtering material, demonstrates synergistic reductions in smoke vapor constituents.

[0003] Cigarettes include tobacco rods or columns which, when burned, produce a particulate phase and a vapor phase. About 70 years ago, filters began to be attached to an end of the tobacco column to, among other things, reduce various smoke components. Filters made from filamentary or fibrous material, such as cellulose acetate tow or paper, reduce the particulate phase of tobacco smoke by mechanical means. However, the fibrous materials are not effective at reducing volatile constituents found in the vapor phase, such as aldehydes, hydrogen cyanide and sulfides. To improve removal of the vapor phase components an adsorbent or absorbent is typically combined with the fibrous filter material.

[0004] Charcoal has a high surface area and is a relatively strong adsorbent for vapor-phase constituents of tobacco smoke. When coated with a mixture of metallic oxides, charcoal is particularly effective in reducing acidic gases. Meerschaum has a large adsorption area with a strong adsorption affinity for charged species, but meerschaum has a considerably low adsorption affinity for non-polar species. Silica gels are generally regarded as weakly retentive adsorbents for vapor-phase constituents of tobacco smoke. Although silica gel readily adsorbs aldehydes and hydrogen cyanide, the constituents also readily desorb from the silica gel. Cation exchange resins have been proposed for nicotine removal. Anion exchange resins have been proposed for the removal of smoke acids, but strongly basic anion exchangers have no effect on smoke vapor phase aldehydes, and weakly basic ion exchange resins—in free base form or as strong, inorganic acid salts thereof—either lack vapor phase filtration properties or have an associated ammonia-based odor which undesirably influences the flavor of tobacco smoke. Weakly basic anion-exchange resins of porous structure are suitable for the removal of smoke acids, but their efficiency diminishes during smoking, as does that of carbon and porous minerals.

[0005] Two or more adsorbents can be used in combination in cigarette filters. For example, U.S. Pat. No. 2,815,760 teaches the use of an ion exchange material with materials which “chemically react with the harmful, nonalkaline and nonacid components of the smoke to form non-volatile compounds, thus retaining the latter to the filter.” However, the aforesaid additives have not yielded satisfactory selective removal of such smoke phase components as smoke aldehydes, particularly acetaldehyde and acrolein. U.S. Pat. No. 4,300,577 teaches the use of a weakly retentive absorbent for vapor-phase constituents intermingled with a second component having mainly primary amine functional groups for the removal of vapor-phase constituents, including aldehydes and hydrogen cyanide from tobacco smoke. However, the filter of the '577 patent has not been shown to demonstrate adequate consumer acceptance or commercial viability.

SUMMARY

[0006] The present invention relates to a cigarette filter that includes a multiple section filter which reduces the level of predetermined smoke constituents. The filter consists of a fibrous filter plug located at the mouth-end of the cigarette, a section containing a selective adsorbent material, and a section containing a general adsorbent material.

[0007] The filter plug can be made from any filter plug material known in the art, such as cellulose acetate tow. The general adsorbent material is preferably selected from a group of relatively high surface area materials, such as activated charcoal, which are capable of adsorbing a range of chemical compounds without a high degree of specificity. The selective adsorbent material is chosen based on the specific smoke constituents targeted for removal. Preferably, the selective adsorbent material is selected from a group of surface functionalized resins, wherein each resin consists of an essentially inert carrier having a sufficient surface area to adsorb the specific smoke constituents. In one embodiment of the present invention, the selective adsorbent material has a phenol-formaldehyde resin matrix surface-functionalized with mainly primary and secondary amine functional groups.

[0008] Structurally, the selective adsorbent material may be positioned adjacent to a tobacco rod and the general adsorbent material positioned between the selective adsorbent section and the filter plug. Alternatively, the general adsorbent material may be positioned adjacent to the tobacco rod and the selective adsorbent material positioned between the general adsorbent section and the filter plug. Preliminary data indicates that the former orientation produces a synergistic effect in smoke constituent reductions relative to the latter orientation. Further, the selective adsorbent and general adsorbent may be interspersed in a traditional filter plug material, such as cellulose acetate, or the adsorbents may be in a close-packed bed or thin layer section within the filter plug material.

SUMMARY OF THE FIGURES

[0009]FIG. 1 is an exploded view of a prior art filter-tipped cigarette;

[0010]FIG. 2 is a perspective view of a filter for a cigarette made in accordance with the present invention wherein the adsorbents are dispersed throughout a filter plug material, and the general adsorbent section is positioned between the filter plug and the selective adsorbent section;

[0011]FIG. 3 is a perspective view of a filter for a cigarette made in accordance with the present invention wherein the adsorbents are dispersed throughout a filter plug material, and the selective adsorbent section is positioned between the filter plug and the general adsorbent section; and

[0012]FIG. 4 is a perspective view of a filter for a cigarette made in accordance with the present invention wherein the adsorbents are packed as beds within a segment of a filter plug material.

DETAILED DESCRIPTION

[0013] The cigarette filter of the present invention includes a multiple section filter which reduces the levels of predetermined smoke constituents. The filter consists of a fibrous filter plug located at the mouth-end of the cigarette, a section containing a selective adsorbent material, and a section containing a general adsorbent material.

[0014] As shown in FIG. 1 and as is known in the art, a typical filter-tipped cigarette 10 has a filter 30 attached to a tobacco rod 20. The tobacco rod 20 consists of a loose tobacco-containing mixture 22 wrapped in a cigarette paper 24, and the filter 30 includes a filter plug 32 wrapped in a plug wrap 34. A sheet of tipping paper 36 joins the filter 30 to the tobacco rod 20.

[0015] Referring to FIG. 2, in the present invention, a cigarette 110 has a multiple section filter 130 attached to the tobacco rod 20. The filter 130 includes a filter plug 132, a section containing a general adsorbent 134 and a section containing a selective adsorbent 136 wrapped in a plug wrap 135. The filter plug 132 is positioned near a first end 131 of the plug wrap 135, and the selective adsorbent section 136 is positioned near a second end 137. The general adsorbent section 134 is sandwiched between the filter plug 132 and the selective adsorbent section 136. The plug wrap 135 forms a sheath around the filter segments 132, 134, 136 to hold the segments together for ease of handling. The filter 130 is attached to the tobacco rod 20 such that the second end 137 is adjacent to the tobacco rod 20.

[0016] The filter plug 132 is made from a filamentary or fibrous material and provides a clean, neat appearance at the mouth end 131 of the cigarette. The filter plug 132 also retains a firmness at the mouth end 131 as the cigarette 110 is consumed. As is known in the art, the filter plug 132 can be made from a variety of materials, among the most common being cellulose, cellulose acetate tow, paper, cotton, polypropylene web, polypropylene tow, polyester web, polyester tow or combinations thereof. Optionally, a plasticizer may be included. Further, the filter plug 132 may carry liquid additives or flavoring agents, and it may include tubes or apertures at preselected positions to provide a more consumer acceptable product, as are known in the art. Functionally, the filter plug 132 captures particulate matter from the tobacco smoke as the cigarette 110 is burned.

[0017] The general adsorbent section 134, shown in FIG. 2, is positioned between the filter plug 132 and the selective adsorbent section 136 of the cigarette filter 130 and consists of a general adsorbent material 144 dispersed throughout a filter plug material 142, such as in a “dalmatian” filter, known in the art. The general adsorbent material 144 is preferably selected from a group of relatively high surface area materials which are capable of adsorbing smoke constituents without a high degree of specificity. For example, the general adsorbent can be selected from activated charcoal, activated coconut carbon, activated coal-based carbon, zeolite, silica gel, meerschaum, aluminum oxide or combinations thereof are among the more common general adsorbents known in the art. Other general adsorbents which may be used include a coal-based charcoal made from semi-anthracite coal with a density about 50% greater than coconut-based charcoal (available from Calgon Carbon, Pittsburgh, Pa.), a carbonaceous resin derived from the pyrolysis of sulfonated styrene-divinylbenzene, such as Ambersorb 572 or Ambersorb 563 (available from Rohm and Haas, 5000 Richmond Street, Philadelphia, Pa. 19137), other materials having similar particle sizes, surface area, and binding affinities, or combinations thereof. To further enhance the efficacy of the general adsorbent, metal oxides or other metal-based complex may optionally be included in or impregnated on the general adsorbent section.

[0018] As shown in FIG. 2, the selective adsorbent section 136 is positioned near the tobacco rod end 137 of the filter 130 and consists of a selective adsorbent material 146 dispersed throughout a filter plug material 142, such as in a “dalmatian” filter, known in the art. The selective adsorbent material 146 is preferably selected based on the material's 146 specificity for a predetermined class of chemical compounds. For example, the selective adsorbent material 146 may be an ion-exchange resin, such as Duolite A7 (available from Rohm and Haas, 5000 Richmond Street, Philadelphia, Pa. 19137), or a material having similar functional groups and binding affinities. The Duolite A7 has a phenol-formaldehyde resin matrix and is surface-functionalized with primary and secondary amine groups, thereby enhancing the resin's specificity toward the aldehydes and hydrogen cyanide found in tobacco smoke.

[0019] Further, the selective adsorbent material 146 must be selected taking into consideration that the contact conditions between the tobacco smoke and the adsorbent 146 are dependent on a number of variables, including how strongly the smoker draws the smoke through the filter as the cigarette is being smoked and how much of the tobacco rod has been consumed prior to each puff. Thus, it is advantageous that the selective adsorbent 146 have a sufficient surface area to ensure that the surface functional sites are easily accessible but such that there is minimal diffusional resistance. As one example, a resin having a surface area of greater than about 35 m²/g can adsorb the smoke constituents and minimize the probability of the resin packing so tightly that the smoke stream is impeded as it passes through the filter. In general, materials with greater surface areas also demonstrate less noticeable performance decline if part of the surface is covered with a plasticizer, as might occur when the adsorbent 146 is dispersed in the filter plug 142.

[0020] When the cigarette is consumed, the tobacco smoke is inhaled by the smoker through the filter 130. In the embodiment of FIG. 2, the smoke initially passes over the selective adsorbent section 136 where the targeted smoke constituents are adsorbed on the surface of the selective adsorbent material 146 and particulate matter in the smoke is retained by the filter plug material 142. The remaining smoke then passes over the general adsorbent section 134 where other polarized constituents may be retained by the adsorbent material 144 and additional particulate matter is retained by the filter plug material 142. Finally, the remaining smoke then passes through the filter plug 132 where additional particulate matter can be reduced. The filtered smoke is then delivered to the smoker.

[0021] As shown in the embodiment of FIG. 3, a cigarette 210 includes a multiple section filter 230 with the filter plug 132 positioned at the mouth end 131, the general adsorbent section 134 positioned near the tobacco-rod end 137, and the selective adsorbent section 136 sandwiched between the filter plug 132 and the general adsorbent section 134. With the alternative relative positioning of the general adsorbent section 134 and selective adsorbent section 136, during a normal puff, the smoke vapor first passes through the general adsorbent section 134, then through the selective adsorbent section 136, and finally through the filter plug 132.

[0022] In the filters 130, 230 of FIGS. 2 and 3, the selective adsorbent material 146 and the general adsorbent material 144 are dispersed throughout the filter tow 142. Dispersion of the adsorbents 144, 146 provides some advantages from a production perspective. Specifically, when the adsorbents 144, 146 are dispersed within the tow 142, the adsorbents are easier to handle than they are as loose particles. However, when the adsorbents 144, 146 are dispersed within the tow 142, there is a risk that any plasticizer which is used on the tow 142 will affect the surface of the adsorbents 144, 146, thereby reducing the adsorption capacity. As shown in the embodiment of FIG. 4, a cigarette 310 includes a filter 330 wherein the adsorbents 144, 146 are packed within the filter plug material 142 as a close-packed bed or thin layer section of general adsorbent 344 and as a close-packed bed or thin layer section of selective adsorbent 346. Because the layer packed adsorbents 344, 346 would not be exposed to the same level of plasticizer as the tow-dispersed adsorbents 144, 146, the adsorbents 344, 346 would retain more available surface area for interacting with smoke constituents. Optionally, a bed of general adsorbent 344 may be combined with a “dalmatian” specific adsorbent section 136, or a bed of specific adsorbent 346 may be combined with a “dalmatian” general adsorbent section 134. When these mixed section filters are used, the adsorbent bed 344, 346 may be either adjacent to the tobacco rod 20 or sandwiched between the “dalmatian” section 134, 136 and the filter plug 132.

[0023] In the embodiments shown herein, the filter plug 132 is positioned at the mouth-end of the filter, with the general adsorbent section and the selective adsorbent section positioned between the filter plug and the tobacco rod. This configuration is expected to be the most consumer acceptable because the adsorbent materials are not visible to the consumer. However, it is understood that the filter would function as intended if either the general adsorbent section or the selective adsorbent section was positioned at the mouth-end of the filter. Further, the term “filter plug” as used herein refers to a dispersion of the filter plug material, and as such, the filter plug may be contiguous with the general adsorbent section and / or with the selective adsorbent section.

[0024] Referring again to FIGS. 2 and 3, an advantage of the cigarette 110 of FIG. 2 as compared to the alternative cigarette 210 of FIG. 3 is that the smoke passes over the selective adsorbent material 146 before passing over the general adsorbent 144. This allows the selective adsorbent 146 to reduce some specific smoke constituents before the general adsorbent 144 is exposed to the smoke, thereby allowing the general adsorbent 144 to be more effective in reducing the remaining smoke constituents. Thus, there is a synergistic effect observed for the adsorbents in the cellulose acetate/general adsorbent/specific adsorbent orientation as compared to the cellulose acetate/specific adsorbent/general adsorbent orientation. For example, a cellulose acetate/40 mg charcoal/40 mg Duolite A7 filter 130 attached to a tobacco rod 20 designed to deliver about 10 mg tar is more effective at reducing hydrogen cyanide, methanol, crotonaldehyde, acrolein, acetaldehyde, propionaldehyde, acetonitrile, methyl ethyl ketone, hydrogen sulfide, propionitrile, acetone, 2-methylpropanal, benzene, toluene, isoprene, furan, acrylonitrile, 1,3-butadiene, and carbon disulfide than a cellulose acetate/40 mg Duolite A7/40 mg charcoal filter 230 attached to a tobacco rod 20 designed to deliver about 10 mg tar.

[0025] The following examples and associated performance data are representative of the cigarettes which can be prepared in accordance with the present invention and the smoke constituent removal performance of those cigarettes. The cigarettes presented are intended for example purposes only and are not intended to be limiting in scope.

EXAMPLE 1

[0026] A multiple section filter 110 is prepared as shown in FIG. 2 wherein the filter plug 132 is made of cellulose acetate tow and is about 7 mm in length, the general adsorbent section 134 consists of about 40 mg of activated coconut charcoal 144 dispersed throughout plasticizer-treated cellulose acetate tow 142 cut to deliver a section 134 about 10 mm in length, and the selective adsorbent section 136 consists of about 40 mg of Duolite A7 dispersed throughout plasticizer-treated cellulose acetate tow 142 cut to deliver a section 136 about 10 mm in length. The filter is attached to a tobacco rod 20 having a length of about 83.5 mm and containing about 617 mg of a typical non-menthol cigarette blend wrapped in a 50 Coresta cigarette paper with about 1.8% citrate. The cigarette delivers about 10.3 mg tar per cigarette.

EXAMPLE 2

[0027] A multiple section filter 210 is prepared with the section orientations as shown in FIG. 3 wherein the filter plug 232, the general adsorbent section 234, and the selective adsorbent section 236 are essentially identical to the filter plug 132, the general adsorbent section 134, and the selective adsorbent section 136 of Example 1. The filter is attached to a tobacco rod 20 having a length of about 83.5 mm and containing about 617 mg of a typical non-menthol cigarette blend wrapped in a 50 Coresta cigarette paper with about 1.8% citrate. The cigarette delivers about 10.0 mg tar per cigarette.

EXAMPLE 3

[0028] Cigarettes are prepared as in Example 1 except that about 20 mg Duolite A7 is used in the selective adsorbent section 136 instead of 40 mg. The cigarette delivers about 10.2 mg tar per cigarette.

EXAMPLE 4

[0029] Cigarettes are prepared as in Example 2 except that about 20 mg Duolite A7 is used in the selective adsorbent section 136 instead of 40 mg. The cigarette delivers about 10.9 mg tar per cigarette.

EXAMPLE 5

[0030] Cigarettes are prepared as in Example 1 except that about 60 mg Duolite A7 is used in the selective adsorbent section 136 instead of 40 mg. The cigarette delivers about 10.0 mg tar per cigarette.

EXAMPLE 6

[0031] Cigarettes are prepared as in Example 2 except that about 60 mg Duolite A7 is used in the selective adsorbent section 136 instead of 40 mg. The cigarette delivers about 10.3 mg tar per cigarette.

EXAMPLE 7

[0032] Cigarettes are prepared as in Example 1 except that about 69 mg of a coal-based charcoal made from semi-anthracite coal is used in the general adsorbent section 136 instead of 40 mg of activated coconut charcoal. The cigarette delivers about 10.1 mg tar per cigarette.

EXAMPLE 8

[0033] Cigarettes are prepared as in Example 2 except that about 69 mg of a coal-based charcoal made from semi-anthracite coal is used in the general adsorbent section 136 instead of 40 mg of activated coconut charcoal. The cigarette delivers about 10.2 mg tar per cigarette.

[0034] Representative cigarettes of Examples 1-8 are smoked to a butt length of about 4 mm using a Borgwalt RM-20 smoking machine. Following the procedures set forth by the FTC, smoke constituents exiting the filter end of each cigarette are passed through a Cambridge filter pad, the vapor phase is collected in a bag and analyzed by GC/MS. The average vapor phase yields expressed in μg/cig are set forth in Table I. TABLE I Cigarettes Prepared by Example: 1 2 3 4 5 6 7 8 General Adsorbent 40 mg activated 40 mg activated 40 mg activated 69 mg charcoal from coconut charcoal coconut charcoal coconut charcoal semi-anthracite coal Selective Adsorbent Duolite A7 Duolite A7 Duolite A7 Duolite A7 mg Duolite/cigarette 40 20 60 40 Filter Segment Order CA/G/S CA/S/G CA/G/S CA/S/G CA/G/S CA/S/G CA/G/S CA/S/G mg tar/cigarette 10.3 10.0 10.2 10.9 10.0 10.3 10.1 10.2 Acetaldehyde 340.8 333.7 388.3 377.4 320.3 320.2 346.8 371.5 Isoprene 238.3 240.4 257.1 268.3 227.4 234.0 227.3 274.3 Acetone 148.4 163.5 159.1 174.9 148.0 155.9 140.0 165.5 Methanol 108.0 127.6 116.8 155.6 111.7 101.5 96.1 137.4 Acetonitrile 61.6 72.0 68.3 84.4 62.8 59.0 62.0 86.3 Acrolein 30.5 31.4 34.3 35.1 28.5 30.8 9.9 36.0 Methyl ethyl ketone 30.2 35.9 31.5 42.0 30.1 32.5 28.6 40.6 Propionaldehyde 26.5 27.4 29.9 31.1 25.3 25.7 26.7 30.8 1,3-Butadiene 26.3 25.9 28.1 27.8 25.8 25.7 25.7 28.3 Formaldehyde 24.2 25.8 26.0 27.2 22.1 25.2 na na Toluene 23.2 25.3 22.4 30.0 23.9 23.2 18.9 24.7 Benzene 21.2 23.6 22.0 26.3 21.1 22.0 21.5 27.8 Acrylonitrile 17.3 17.7 18.4 19.6 17.0 17.0 7.6 9.2 Furan 16.7 17.0 17.6 17.9 16.4 16.7 17.2 18.8 Hydrogen cyanide 15.6 16.4 21.1 21.4 13.6 15.2 16.9 19.9 Hydrogen sulfide 13.3 13.0 14.3 14.1 13.1 13.1 14.8 14.4 Propionitrile 13.3 15.0 13.8 17.3 13.6 13.2 15.9 20.7 2-Methylpropanal 6.6 6.7 7.1 7.6 6.6 6.6 13.1 15.1 Crotonaldehyde 5.3 5.9 5.6 6.9 5.3 5.2 3.3 5.2 Carbon disulfide 2.6 2.6 2.8 2.8 2.6 2.6 2.8 2.9 Styrene 2.1 1.8 2.2 2.1 2.1 1.7 1.8 2.1 Pyridine 2.0 1.9 1.9 2.0 1.9 1.9 1.3 1.4

[0035] From a reading of the above, one with ordinary skill in the art should be able to devise variations to the inventive features. For example, the filter plug, the general adsorbent section, and the selective adsorbent section may vary in length and diameter, relative to any dimensions specified herein and relative to each other. Further, the various section dimensions may be optimized for a particular tobacco blend or for particular tobacco rod dimensions. These and other variations are believed to fall within the spirit and scope of the attached claims. 

What is claimed is:
 1. A multiple section cigarette filter comprising: (a) a fibrous filter plug; (b) a selective adsorbent section, comprising a selective adsorbent material having an affinity for a predetermined class of chemical compounds; and (c) a general adsorbent section, comprising a general adsorbent material having a high surface area and being capable of adsorbing smoke constituents without a high degree of specificity, said fibrous filter plug, said selective adsorbent section, and said general adsorbent section being in tandem and circumscribed with a plug wrap.
 2. The cigarette filter of claim 1 wherein said selective adsorbent material is an ion-exchange resin.
 3. The cigarette filter of claim 2 wherein said selective adsorbent material has a surface area sufficient to ensure that the surface functional sites are easily accessible to a smoke constituent.
 4. The cigarette filter of claim 2 wherein said ion-exchange resin has a phenol-formaldehyde resin matrix and is surface-functionalized with primary and secondary amine groups.
 5. The cigarette filter of claim 2 wherein said selective adsorbent section comprises said selective adsorbent material dispersed throughout a fibrous material.
 6. The cigarette filter of claim 2 wherein said selective adsorbent section comprises a close-packed bed of said selective adsorbent material.
 7. The cigarette filter of claim 1 wherein said general adsorbent material is selected from the group consisting of activated charcoal, activated coconut carbon, activated coal-based carbon, zeolite, silica gel, meerschaum, aluminum oxide, a coal-based charcoal made from semi-anthracite coal, a carbonaceous resin derived from the pyrolysis of sulfonated styrene-divinylbenzene, or combinations thereof.
 8. The cigarette filter of claim 7 wherein said general adsorbent section comprises said general adsorbent material dispersed throughout a fibrous material.
 9. The cigarette filter of claim 8 wherein said general adsorbent section further includes an additive selected from a metal oxide or a metal-based complex.
 10. The cigarette filter of claim 7 wherein said general adsorbent section comprises a close-packed bed of said general adsorbent material.
 11. The cigarette filter of claim 10 wherein said general adsorbent section further includes an additive selected from a metal oxide or a metal-based complex.
 12. The cigarette filter of claim 1 wherein said filter plug is made from cellulose, cellulose acetate tow, paper, cotton, polypropylene web, polypropylene tow, polyester web, polyester tow or a combination thereof.
 13. The cigarette filter of claim 12 wherein said filter plug is made from cellulose acetate tow.
 14. The cigarette filter of claim 12 wherein said filter plug further includes a plasticizer.
 15. The cigarette filter of claim 12 wherein said filter plug further includes a liquid additive.
 16. The cigarette filter of claim 15 wherein said liquid additive is a flavoring agent.
 17. The cigarette filter of claim 1 wherein said general adsorbent section is sandwiched between said fibrous filter plug and said selective adsorbent section.
 18. The cigarette filter of claim 1 wherein said selective adsorbent section is sandwiched between said fibrous filter plug and said general adsorbent section.
 19. A multiple section cigarette filter comprising: (a) a fibrous filter plug; (b) a selective adsorbent section, comprising a selective adsorbent material having an affinity for a predetermined class of chemical compounds dispersed throughout a fibrous material; and (c) a general adsorbent section, comprising a general adsorbent material having a high surface area and being capable of adsorbing smoke constituents without a high degree of specificity, said fibrous filter plug, said selective adsorbent section, and said general adsorbent section being in tandem and circumscribed with a plug wrap.
 20. The cigarette filter of claim 19 wherein said selective adsorbent material is an ion-exchange resin.
 21. The cigarette filter of claim 20 wherein said selective adsorbent material has a surface area sufficient to ensure that the surface functional sites are easily accessible to a smoke constituent.
 22. The cigarette filter of claim 20 wherein said ion-exchange resin has a phenol-formaldehyde resin matrix and is surface-functionalized with primary and secondary amine groups.
 23. The cigarette filter of claim 19 wherein said general adsorbent material is selected from the group consisting of activated charcoal, activated coconut carbon, activated coal-based carbon, zeolite, silica gel, meerschaum, aluminum oxide, a coal-based charcoal made from semi-anthracite coal, a carbonaceous resin derived from the pyrolysis of sulfonated styrene-divinylbenzene, or combinations thereof.
 24. The cigarette filter of claim 23 wherein said general adsorbent section comprises said general adsorbent material dispersed throughout a fibrous material.
 25. The cigarette filter of claim 24 wherein said general adsorbent section further includes metal oxides or other metal-based complex.
 26. The cigarette filter of claim 23 wherein said general adsorbent section comprises a close-packed bed of said general adsorbent material.
 27. The cigarette filter of claim 26 wherein said general adsorbent section further includes metal oxides or other metal-based complex.
 28. The cigarette filter of claim 19 wherein said filter plug is made from cellulose, cellulose acetate tow, paper, cotton, polypropylene web, polypropylene tow, polyester web, polyester tow or a combination thereof.
 29. The cigarette filter of claim 28 wherein said filter plug is made from cellulose acetate tow.
 30. The cigarette filter of claim 28 wherein said filter plug further includes a plasticizer.
 31. The cigarette filter of claim 28 wherein said filter plug further includes a liquid additive.
 32. The cigarette filter of claim 31 wherein said liquid additive is a flavoring agent.
 33. The cigarette filter of claim 19 wherein said general adsorbent section is sandwiched between said fibrous filter plug and said selective adsorbent section.
 34. The cigarette filter of claim 19 wherein said selective adsorbent section is sandwiched between said fibrous filter plug and said general adsorbent section.
 35. A multiple section cigarette filter comprising: (a) a fibrous filter plug; (b) a selective adsorbent section, comprising a selective adsorbent material having an affinity for a predetermined class of chemical compounds dispersed throughout a fibrous material; and (c) a general adsorbent section, comprising a general adsorbent material having a high surface area and being capable of adsorbing smoke constituents without a high degree of specificity dispersed throughout a fibrous material, said fibrous filter plug, said selective adsorbent section, and said general adsorbent section being in tandem and circumscribed with a plug wrap.
 36. The cigarette filter of claim 35 wherein said selective adsorbent material is an ion-exchange resin.
 37. The cigarette filter of claim 36 wherein said ion-exchange resin has a phenol-formaldehyde resin matrix and is surface-functionalized with primary and secondary amine groups.
 38. The cigarette filter of claim 35 wherein said general adsorbent material is selected from the group consisting of activated charcoal, activated coconut carbon, activated coal-based carbon, zeolite, silica gel, meerschaum, aluminum oxide, a coal-based charcoal made from semi-anthracite coal, a carbonaceous resin derived from the pyrolysis of sulfonated styrene-divinylbenzene, or combinations thereof.
 39. The cigarette filter of claim 35 wherein said filter plug is made from cellulose, cellulose acetate tow, paper, cotton, polypropylene web, polypropylene tow, polyester web, polyester tow or a combination thereof.
 40. The cigarette filter of claim 39 wherein said filter plug is made from cellulose acetate tow.
 41. The cigarette filter of claim 39 wherein said filter plug further includes a plasticizer.
 42. The cigarette filter of claim 39 wherein said filter plug further includes a liquid additive.
 43. The cigarette filter of claim 42 wherein said liquid additive is a flavoring agent.
 44. The cigarette filter of claim 35 wherein said general adsorbent section is sandwiched between said fibrous filter plug and said selective adsorbent section.
 45. The cigarette filter of claim 35 wherein said selective adsorbent section is sandwiched between said fibrous filter plug and said general adsorbent section. 